This invention relates to a self-switching electric cord reel adapted for electrical connection to portable electric appliances.
Electric cord reels have been in use for many years, such as for paying out and receiving electric cord for lead lights, various electrical household appliances like sweepers, light guards, sometimes referred to as trouble lights, and in general wherever insulated electric conductors are to be optionally extended and retracted with respect to a relatively stationary point.
As an example, in many service areas, such as automotive service stations, machine shops, and the like, it is helpful for a workman to have a portable trouble light which he can carry to and secure about a work site in order to provide better illumination. Electric cord reels are commonly used to support and electrically energize such portable lights. The reel is fixed at a suitable location. A sufficient length of electric cord is then pulled from the reel to place the trouble light or the like at a desired location. When the workman is finished, the cord is rewound onto the reel.
Previously, trouble lights, light guards, and other electrical appliances useful with an electric cord reel have had a switch located directly on the appliance, so that a worker could easily and conveniently turn the appliance on and off at that point. However, this practice can present a safety hazard in that electric short circuits and shocks are thought more apt to result due to wearing or damage to the switch over a period of use. Governmental regulations may also require that electrical appliances like trouble lights do not have switches or other likely points of electrical contact on or near the appliance.
While exterior designs may vary, electric cord reels basically comprise a reel and shaft mounted to rotate relatively to each other; cooperating ratchet and pawl means carried by the shaft and reel to arrest the turning of a reel at one of several selective rotary stations when the length of the cord paid out reaches a desired length; a coiled spring designed to rotate the reel in an opposite direction and rewind the cord back onto the reel when the ratchet and pawl means are disengaged; and electrical input means for energizing the insulated electrical cord itself.
U.S. Pat. No. 3,904,843 to Joseph A. Kendechy discloses a self-retracting reel for an electric cord that is self-switching at the reel. Automatic switching of current in the electric cord occurs in response to whether the cord is wound or unwound from the reel.
The often reversing rotary movement of a reel creates mechanical shocks on the reel construction which are often augmented by jerking the electric cord or otherwise mistreating the reel during use. In this manner, a reel can be subjected to undue stress and strain, thereby shortening its useful life. In a reel of the type proposed in the cited Kendechy patent, mechanical shocks and vibrations on the reel and especially on the switch mounted on the reel are further induced by a lever mounted on the reel housing which pivots to open and close the switch by direct contact with it.
The switch of the Kendechy patent is also a rather complicated microswitch which requires added structure and detail on the reel, not only to operate the switch but to protect it against damage. Thus, Kendechy uses a microswitch having an operating arm and roller means attached to the free end of the arm. A cover which partially encloses the microswitch construction on the Kendechy reel is mounted on a side of the housing and provided with window means formed in its edge through which extends the roller means of the microswitch arm. A stop attached to the electric cord trips a lever which engages the roller means at the end of the microswitch operating arm and thereby operates the switch.
U.S. Pat. No. 3,808,382 to Charles H. Blanch and James W. Kovacik discloses an electric cord reel construction which includes a hub portion around which an electric cord is wound. The hub portion has a limited degree of free radial movement with respect to a shaft about which the reel relatively rotates. As a result, the reel is resiliently mounted with respect to the shaft and can absorb or interrupt mechanical jars transmitted to the hub portion. In use, the hub portion has a limited resilient movement radially of the reel which can be effected by sudden or excessive pulls or jerks upon the electric cord. However, such movement cannot exceed a predetermined amount, since it is checked upon eventual contact by the hub portion with another member of the reel.